diff --git a/src/hooks/use-chat.ts b/src/hooks/use-chat.ts
index d92fce9..876c434 100644
--- a/src/hooks/use-chat.ts
+++ b/src/hooks/use-chat.ts
@@ -26,8 +26,6 @@ export interface ChatMessage {
   isLoading?: boolean;
   /** Tool calls in progress or completed during this assistant turn */
   toolCalls?: ToolStatus[];
-  /** Structured content blocks for multi-turn context (sent to API) */
-  contentBlocks?: any[];
   /** Clickable entity suggestions for disambiguation */
   suggestions?: EntitySuggestion[];
 }
@@ -115,10 +113,12 @@ export function useChat(context?: ChatContext) {
       setIsLoading(true);
 
       try {
-        // Build message history for the API, preserving structured content blocks
+        // Build message history for the API — send plain text only.
+        // Tool interactions are resolved server-side within a single request,
+        // so we never send tool_use/tool_result blocks back in history.
         const apiMessages = [...messages, userMsg].map((m) => ({
           role: m.role,
-          content: m.contentBlocks || m.content,
+          content: m.content,
         }));
 
         abortRef.current = new AbortController();
@@ -194,10 +194,6 @@ export function useChat(context?: ChatContext) {
                         provider: data.provider,
                         isLoading: false,
                         suggestions: data.suggestions,
-                        // Store structured blocks for multi-turn context
-                        contentBlocks: data.content
-                          ? [{ type: "text", text: data.content }]
-                          : undefined,
                       }
                     : m
                 )